Rechargeable battery systems for electric vehicle with purely electric drive and for hybrid vehicles and vehicles with fuel cell drive are the subject of current research. At present, in the said types of vehicle lithium-ion batteries are preferably used, which are distinguished by a high energy density and an only poorly pronounced memory effect. The capability of a rechargeable battery to reliably supply with electric power various electric consumers installed in motor vehicles depends to a considerable extent on the thermal conditions prevailing in the environment of the battery. The electrochemical processes occurring both in the provision and also in the receiving of electric power in the sense of a recharging in the battery are dependent to a not insignificant extent on the operating temperature of the battery. Extensive investigations on different battery systems based on lithium-ion have shown for instance that below a critical temperature, for instance in the range of approximately 0° C., the electrical energy density made available by the battery decreases intensively compared to higher operating temperatures. Below the critical temperature, in addition damage to the li-ion cell can occur during charging.
A crucial factor for a reliable and trouble-free operation of said batteries—this applies not only to said batteries based on lithium-ion, but generally for any desired rechargeable battery systems—is consequently the creation of thermally well-defined environmental conditions. This means, with regard to the considerable temperature fluctuations occurring for instance in a motor vehicle during normal operation, that these must be equalized by suitable temperature control apparatus coupled thermally to the battery. Such a device must be able, on the one hand, to increase the environmental temperature in the immediate vicinity of the battery, if this assumes a value which lies below the permissible temperature range. On the other hand, the possibility must also exist to reduce the environmental temperature, if this does not upwardly exceed said temperature interval.
Various temperature apparatuses, able to be thermally coupled to a battery, are known from the prior art, which generally comprise both a heating unit for increasing the battery temperature and also a cooling system for reducing the battery temperature.
Thus in DE 10 2009 90 588 19 A1 a device is described for heating and cooling a battery, which has a coolant circuit and at least on electrical heating element, which are both arranged in a common heat transfer component. The electrical heating element is connected here in a form-fitting and/or force-fitting manner to the heat transfer component. It is characteristic for the device that it requires a relatively large number of components, which during a heating process are also heated by the heating element, due to the construction, which distinctly increases the heating output necessary for the heating of the battery which is actually aimed for.
It is an object of the present invention to provide an improved temperature control apparatus for a power supply unit, which realizes an effective thermal coupling to this power supply unit and at the same time is distinguished by a simple structural composition with a small number of components. A further object of the invention consists in providing a temperature control arrangement with at least one such temperature control apparatus.
This problem is solved by the subject of the independent claims. Preferred embodiments are the subject of the dependent claims.